Wear reducing rounds having gun barrel additive dispensing means embodied in either the projectile or its associated cartridge which do not substantially interfere with the desired firing mode of the gun into which the round is placed are known. On firing the round an additive is deposited along the barrel to reduce barrel wear by virtue of the additive's lubricating or thermal insulating properties.
The rate of application of a gun barrel wear reducing additive into a gun barrel ideally corresponds to wear severity along the barrel. Wear severity within a rifled gun barrel is typically at its worst in the region of the barrel bore close to the chamber of the gun where rifling commences, in which region the projectile experiences maximum rotational acceleration as it travels along the barrel. Thereafter, wear severity decreases as the projectile approaches the muzzle. The profile of wear severity along the barrel tends to be similar to that of the pressure of the propellant gas behind the projectile as the projectile is accelerated along the barrel.
An additive dispensing means embodied in the cartridge has the disadvantage that the inclusion of additive reduces the volume available for propellant: this is particularly disadvantageous in small arms rounds where the available propellant volume is small.
Additive dispensing means included in the projectile have hitherto relied upon inertial forces to release the additive from a store within the bullet as, for example, in the self-lubricating projectile described in UK Pat. No. 204,306. Such an additive dispensing means has the disadvantage that the additive is concentrated in the region where the projectile experiences maximum acceleration along the gun barrel which is typically one third the way along the barrel.